Posted
by
CmdrTaco
on Wednesday November 15, 2006 @08:33AM
from the having-a-hard-time-buying-it dept.

StrongGlad writes "The tangle of cables and plugs needed to recharge today's electronic gadgets could soon be a thing of the past. Researchers at MIT have outlined a relatively simple system that could deliver power wirelessly to devices such as laptop computers or MP3 players. In a nutshell, their solution entails installing special 'non-radiative' antennae with identical resonant frequencies on both the power transmitter and the receiving device. Any energy not diverted into a gadget or appliance is simply reabsorbed. The system currently under development is designed to operate at distances of 3 to 5 meters, but the researchers claim that it could be adapted to factory-scale applications, or miniaturized for use in the 'microscopic world.'"

From the BBC Article:5) Energy not transferred to laptop re-absorbed by source antenna. People/other objects not affected as not resonating at 6.4Mhz

That was at the bottom of the graphic. So it should be safe (however, seeing as the technology only exists as a computer model and not as reality, I would bet that if there are any safety issues they will only come to light after such a device is actually built)

Well, yes, sure, but how can one get through the metal bulkheads with an electromagnetic signal ? Unless your aircraft is made from some type of material that will allow e and b fields to buzz right through it (and if so, perhaps we can sell that material to various Stealth programs, no ?), you're going to have to cut holes for waveguides instead of cable ways.

The major savings in transmitted power in an aerospace environment would be in weight of wiring. If your transmitter / receiver assembly and waveguide pipes weigh less than the equivalent direct copper power busses, then it's all worth while.

Of course, the most likely savings these days has to do with signal / information cables. Replacing complex multi-wire signal cables with digital network / fiber optic busses is your best chance to cut weight.

Other interesting features of a waveform power transmission solution would need to include power interruption devices, load sensing devices, and the like. If this takes off, I would find some millimeter wave radar companies that want to get in on the 'ground' floor.

Precise tuning and sharp Q factors for resonant circuits are essential for this kind of systems to be useful.

You need a method and means of steering resonant frequency of both receiving and transmitting resonant circuits in a lockstep, synchronizing that offset through covert (encrypted) communication channel between transmitter and receiver, thus ensuring that unauthorized receivers cannot maintain efficiency needed for practical purposes (in fact, they would be "bridged over" by deployed well-tuned receivers, thus getting nothing but crams). Alternatively, pseudo random switched multichannel transmission may be used (frequency hopper).

Global Positioning System may have to be deployed, too, so that synchronization works both in time and space... you know, radio waves have finite velocity! However, for really large distances, propagation would be too unpredictable for that to work reliably, unless fixed frequency circuits are used.

This would be a state of the art high tech, married to Tesla wireless power system. As luck would have it, that would also be the no.1 target of future crackers.

If only we could build a cable where the signal was transmitted on a wire totally encased by an EM shield -- with the interior signal wire running down the central axis of the exterior shield. That would be handy for stopping stray EM on the cable network.

Did you not read the article? The system does not radiate. It's a near field coupling device, like a transformer. It won't interfere with anything that isn't extremely close to it, and that isn't designed to resonate at 6.4MHz

I admit, the idea of using this on lower power devices is sexy. Never charging a cellphone, iPod, laptop, or wireless game controller would be great. I just don't know if I would trust it for heavy duty power needs like appliances and computers. What would the rate of charge on something like this be, btw?

However, I hope they can get a version of this working for electric cars. That would be perfect. A transmitter in the garage at home, a transmitter in the parking structure at work, etc... If they could prove it was safe enough, they might even be able to put them near major freeways. (at least at gas stations/rest stops) Never having to plug the car in would be a big selling point for manufacturers.

You would need to make this pretty idiot-proof, however. What happens if someone accidentally steps on a transmitter? Would that alter it's frequency? What kind of problems would that cause? Furthermore, according to the article, both the transmitter and the receiver need to be at the same frequency for this to work. Does that mean this would be a powered antenna? That seems to me like it would sort of negate the point because you would still need some way to get power into the device if it runs completely dry.

This also opens up some other problems, the largest of which I can think of is theft. There would have to be one or two set frequencies these devices could operate on, so someone else is bound to have a matching receiver. If you are doing this in your home in the suburbs, that's fine, but in a crowded metropolitan area, it would be easy for lots of people to siphon power off your transmitter as well. Even for low-power devices like cellphones, that can add up to a lot of cost over time, the only solution being limiting the range of the device, which defeats the whole point of wireless charging.

Do you live somewhere that has radio stations, tv broadcast, or cellular service? Whether or not you do, you'd better freak out. You're being penetrated by electromagnetic radiation all the time! No matter what you do! No matter where you are!

Was going to mod this insightful until your last sentence. I think I'll jump in here instead...

The problem I have with statements like "withholding freeing knowledge from the populace so that they are more easily controlled" is that they always come up when talking about Tesla. It's like the guy is the ultimate hero of every conspiracy theorist. Whether or not that statement is true isn't my point; my point is that whenever someone brings up Tesla, there's some stereotypical conspiracy theorist who needs to mention that "here was a noble soul who was villaniously downtrodden by the evil corporations of his day."

In some ways it's like the militaristic glorious defeat, or romantic loss. For example, Hannibal's campaign in Italy (and ultimate loss), the Spartan annihlation at Thermopylae, Custer's last stand, etc. There is some set of people that admire losers who lose in romantically noble ways. If Tesla had won at every level and Edisons ideas had lost out, I believe this set of people would post the same theories about Edison instead.

Well, it's still at the basic research stage, and you can bet a good deal of testing, both theoretical and practical, will take place before this ever reaches the market (oh, and I do research at a publicly funded institute which does risk assesment of radiative household products like cell phones, for what that's worth). But from what I read, and I'm not pretending to understand the physics just from reading the BBC article, the point is the power would not be radiating, unless it was absorbed by a co-resonating antenna.

Without more research, I can't say how well that works, but if it does what the article says it does, the power would not be radiating unless it was coupled with the receiver. This would mean that should you absorbe the radiation, there would be no more radiation. It might sound like voodoo physics, but not necessarily. Again, I'd have to look at something more technical before making comment. But the guys at MIT rarely publish bullshit.

Speaking of which, what moron tagged this 'vaporware'? It's basic research from MIT for chrissakes. That has nothing to do with vaporware.

This unfortunately seems to be a case of "cargo cult science". It looks like science, but isn't. I just got hold of the actual paper on arXiv.org, and some comments after quickly browsing through are:

1) It is a purely theoretical study made by a physicist, who evidently has little experience within RF engineering. With such a "simple" concept, why didn't he bother making a quick experiment? (Spoiler warning: Many beatiful theories have been killed at infancy by experiments...)

2) He is assuming totally unrealistic Q-values.

3) He doesn't explain how he will get the RF energy into and out of the resonators. The Q-value of these circuits would load his resonators.

4) He is using ridiculous precision in his results (6 significant digits...)

5) Magnetic coupling between tuned circuits has been known for ages, but then of course cast in its standard EE terminology. Now a physicist has rediscovered it...

6) "Publication by press release". Making exaggerated claims in the media is no substitute for peer review (where the peers are within the correct field).